Young, athletic and at risk for sudden death?

From the battlefield near a Greek town called Marathon, a young man named Pheidippides ran 26 miles and 385 yards to Athens to announce the defeat of the Persians. And then he collapsed, perhaps becoming the index case for sudden cardiac death in an athlete.

Since that event of legend there have been countless other cases, including tragic stories of promising high school athletes whose lives were cut short.

How common is sudden cardiac death in young athletes? Not very. Estimates vary, from one in 50,000 to one in 500,000. In the United States, sudden cardiac death most commonly strikes football and basketball players; in Europe, soccer players.

While atherosclerosis is blamed for most cardiac deaths in older athletes, sudden death in players under 35 is typically caused by congenital abnormalities.

A study of sudden deaths in trained young athletes found that the majority died of hypertrophic cardiomyopathy at a median age of 17. With this condition, the intraventricular septum is significantly thickened, causing a hypotensive response to exercise. Abnormalities in the myocardium increase the risk of malignant heart rhythms. In 90 percent of the cases studied, death occurred during peak activity or immediately after.

Other cardiac conditions that pose a risk to athletes include:

Coronary anomalies. Exercise can lead to kinking of arteries or compression between the aorta and pulmonary artery. This can lead to low blood supply to the heart muscle and to lethal heart rhythms.

Myocarditis. Inflammation of the heart may weaken the muscle, leading to ventricular arrhythmias. This condition may be caused by a viral infection, although the cause is often unknown.

Commotio cordis. Blunt, nonpenetrating and innocent-appearing blows to the chest can produce ventricular fibrillation. Even moderate force from projectiles, such as a baseball or hockey puck can cause death, particularly in younger people with more flexible chest walls.

Identifying athletes at risk

A definite diagnosis of hypertrophic cardiomyopathy would exclude an athlete from participating in most competitive sports. But the challenge for many physicians is detecting risk in seemingly healthy players. And while the incidence of sudden death during sports is low, screening for cardiac abnormalities is a topic of much discussion.

Studies of athletes who died showed that many had no cardiac symptoms and had passed general health screenings. Some underlying cardiac conditions might have been picked up with a screening ECG or echocardiogram. Conversely, ECGs or even echocardiograms can result in false positives because of “athlete’s heart” – a term referring to changes that are normal for high-performing athletes, such as enlarged chambers or wall thickening.

Despite its limitations, however, pre-participation cardiovascular screening with a focused history and physical examination enjoys overwhelming public support and the endorsement of the American Heart Association. The association suggests including these questions when taking an athlete’s medical history:

Do you experience chest pain or discomfort with exertion?

Have you ever passed out or almost passed out?

When you exert yourself or exercise, do you experience shortness of breath or fatigue that seems out of proportion to the level of exercise or exertion?

Have you ever been told you have a heart murmur?

Have you ever been diagnosed with high blood pressure?

Have any of your relatives died suddenly before age 50 from heart disease or an unknown cause?

Do any of your relatives under the age of 50 have a disability from heart disease?

Do any of your family members have any of the following heart conditions?